Ionization chambers



May 17, 1960 J. WEILL IONIZATION CHAMBERS Filed Oct. 7. 1954 United States Patent -i2,9s1,2s2 7 .IONIZATION CHAMBERS Jacky :Weillplaris, France, assignor to'Commissariat .a lEnergie Atomique', Paris, France, an oflicial body .of France Applicationflctober 7, 1954, Serial No. 460,975

Claimspriorltmapplication FranceJuly 9, 1954 2 Claims. (Cl. 250-836) The present; invention relates: to ionization chambers, and. more .particularly to ionization .chambers .having a hollow. cathode and an anode arranged within the hollow cathode.

"lt isian object ofthe present invention to reduce. the leakage resistance between the electrodes .!Of the. ionization chamber.

.Otherobjects and advantages of thepresentinvention will be apparent from the'following detailed description thereof in connection with the drawings attached hereto and forming part of this specification. The drawings show, by way of example, some embodiments of the present invention.

In the drawings:

Fig. 1 is a wiring diagram of a first embodiment of the present invention;

Fig. 2 is a wiring diagram of a second embodiment of v terior of which is arranged a battery 4 preferably con sisting of a column of series-connected cells, for instance of a Zamboni pile forming a rigid body. One of the terminals, for instance the positive one, of the battery 4 is connected with the hollow second electrode 2 called the collecting electrode, whereas the negative terminal of said battery is rigid with a connection or support 4a extending through a member 3 made of insulating material and having the shape of a stopper inserted into a hole of the end wall of the first electrode 1. A resistor R connects the rigid support 4a outside the ionization chamber 1 with a preferably grounded connection In electrically connected to the first electrode 1.

The operation of this device is as follows:

The ionization chamber indicates radiations in a manner well known in the art. The terminals A and B of the device are either at the same potential, namely when there is no current flowing through the ionization chamber 1, or at a negligible potential difierence when a signal current flows through the ionization chamber 1. Thus, it is seen that the insulating material of the stopper 3 is not subjected to a substantial electrical voltage and consequently will not transmit any leakage currents.

Referring now to Fig. 2 of the drawings, the embodiment shown in this figure difiers from that shown in Fig. 1 only by the arrangement of the resistor R which is ar ranged inside the envelope or first electrode 1 and connects the same with the rigid connection 4a between the negative terminal of the battery 4 and the stopper 3.

Otherwise the embodiment shown in Fig. 2 is the same Referring now to Fig. 3 of the drawings showing a structural embodiment of the present invention,a cylindrical envelope 1 consisting of a suitable syntheticresin, glass or a similarinsulating. material is provided on its inner.su rface with an electro-conductive coating or layer 5 incontact with springs 6 more fully to be described hereinafter. The cylindrical envelope'l is closed by two end walls 7 and 8 which form together with the envelope 1 a vacuum-tight ionization chamber containing a' suitable fgas at a suitable low pressure. The end wall 7 is provided with a central boring in which a metal1ringshaped member 10 corresponding to the terminal B shown in Figs. land 2. As will be seen from the drawing the contact springs'6 are carried by the end wall'7 to which they are attached by screws such as 11. .Each spring'6 has a fiat middle portion .11 through which .the screws 11 extend and which is arranged so as to lie, flat againstthe end wall 7. The inner end13 of eachof the springs 6 touches'the. electroconductive ring 10 whereas the outer end 14 of each contact spring 6 forms a contact member formed. as a circular arc in electrical contact with the conductive layer 5 of the cylindrical envelope 1. Thus it will be seen that the .electroconductive' layer Storms a first electrode connected by the contact springs 6 with the electroconductive ring 10 forming the analogue of the member B shown in Figs. 1 and 2.

The electroconductive member 10 has a central opening 15 which accommodates an insulating stopper 3 preferably consisting of polystyrene and having a central boring through which a metal rod 17 extends. The metal rod 17 carries a screw thread on which a nut 18 is screwed. Between a washer 19 and the insulating body or stopper 3 is clamped one end of a curved contact spring 20 which contacts the insulated entrance member 21 of a pre-amplifier 22. The insulated entrance member 21 is the analogue of the terminal A shown in Figs.

1 and 2.

The rod 17 extends beyond the insulating stopper 3 through a distance piece 23 and carries a battery such as a Zamboni pile 4 having a voltage of eg 200 volts. As will be seen from the drawing, the rigid connection 17 is connected to the negative terminal 24 of the Zamboni pile 4 whereas the positive terminal 25 thereof is rigidly connected to a rigid contact rod 26 being in screw connection with a second rigid contact rod 27 rigidly connected to the apex 28 of a hollow second electrode 2 which surrounds the Zamboni pile 4 and extends as far as the negative terminal 24 thereof. An insulating ring 29 is arranged as a spacing member between the open end of the hollow second electrode 2 and the negative terminal of the Zamboni pile 4. Thus, it will be seen that the second electrode 2 is rigidly supported by the Zamboni pile 4 which in turn is rigidly supported by the electroconductive rod 17 connected by the contact spring 20 to the entrance member 21 of the preamplifier 22. In consequence thereof the Zamboni pile 4 and the inner electrode 2 form a rigid assembly. The electroconductive rod 17 is in turn mechanically fixed and supported by the insulating member 3 rigidly supported by the electroconductive member 10 screwed in the end wall 7 of the envelope 1.

It has been found that insulated bodies such as 3 and metal rods such as 17 which are sufficiently strong, can be replaced by ceramic lead-in terminals used in condenser construction (not shown) or high voltage lead-ins (not shown) well known per se in the art, one of the terminals of which takes the part of the metal rod.

lt should be understood that numerous changes may be made in the form, construction, and arrangement of the several parts of ionizing chambers illustrated herein without departing from the spirit and scope of my invention or sacrificing any of its attendant advantages, the

ionizing chambers herein described being merely for the purpose of illustrating the invention.

What 1 claim is: a

1. An ionization chamber which comprises, in combination, a first electrode forming a closed substantially cylindrical envelope, a battery in the form of a rigid body of cylindrical shape located within said first electrode out of contact therewith and in substantially c0- axial relation therewith, a conductor rigidly connected with one terminal of said battery extending through an end wall of said envelope, insulating means for securing said conductor to said end Wall at the place where said coriducotr passes through said end wall, whereby said battery is supported in said first electrode through said conductor, a second electrode of tubular shape, mounted coaxially on said battery within said first. electrode at a distance therefrom, saidsecond electrode being insulated from said conductor, means for'connecting the other terminal of said battery with said second electrode, and a resistor inserted between said conductor and said first electrode fordetecting a potential difference between them due to ionization of the gaseous medium in said first electrode.

2. An ionization chamber which comprises, in combination, a first electrode forming a closed envelope, a battery in the form of a rigid body located within said first electrode out of contact therewith, a conductor rigidly connected with one terminal of said battery extending through an end wall of said envelope, insulating means for securing said conductor to said end wall at the place where said conductor passes through said end wall, whereby said battery is supported in said first electrode through said conductor, a second electrode mounted on said battery within said first electrode at a distance therefrom, said second electrode being insulated from said conductor, means for connecting the other terminal of said battery with said second electrode, and a resistor inserted between said conductor and said first electrode for detecting a potential diiference between them due to ionization of the gaseous medium in said first electrode.

References Cited in the file of this patent UNITED STATES PATENTS 

